I. Field of the Invention
The present invention relates to concussion-resistant helmets worn by the riders of recreational vehicles such as motorcycles, dirt bikes, ATVs, snowmobiles power boats and the like. More specifically, the present invention relates to improving sound suppression for such helmets.
II. Related Art
Millions of people throughout the world participate in and enjoy recreational motor sports such as motorcycling, snowmobiling and power boating. However, at the end of a long day on the road, trail or water a rider of a recreational vehicle used in such sports will experience fatigue, a ringing sensation in his or her ears, and a loss of hearing that can last for days or even become permanent. This is due in part to the sounds generated by the engine of such a vehicle and the rider's close proximity to the engine for an extended period of time. Another significant contributing factor is wind noise produced around the rider's head while the rider is in motion.
By way of example, when a motorcycle rider is stopped at a stop light of a busy intersection with a standard helmet on and the visor close the rider experiences sound levels of 80 to 90 decibels. When the motorcycle is in motion and traveling at speeds between 35 miles per hour and 65 miles per hour, wind noise in such a helmet is the range of 110 to 116 decibels or even higher. At these exposure levels, the exposure time should be limited to no more than fifteen minutes a day to prevent hearing loss. The story is the same for snowmobile riders. Snowmobiles generate sound at about 105 decibels and the same wind noise will be encountered at the same speeds irrespective of the vehicle being ridden. Riders who do not wear a helmet at all (or wear skull caps or half shell models as opposed to a standard full coverage helmet) experience ten times more wind noise.
Many states place no restrictions on the noise generated by motorcycles, snowmobiles and other recreational vehicles. Those states that have adopted statutes or regulations placing restrictions on the noise generated by such vehicles have done so for the benefit of pedestrians and other bystanders rather than to protect the hearing of riders. For example, Michigan has adopted a sound restriction related to motorcycles of 86 decibels, but the measurement is taken 50 feet from the motorcycle when the motorcycle is traveling at more than 35 miles per hour. The sound level at the motorcycle itself and experienced by the rider is much higher due to proximity to the motorcycle. Also, the pedestrian's exposure to the noise generated by a particular motorcycle is often very brief. Riders are often exposed to such noise for hours at a time. New Hampshire's regulation does measure noise 20 inches from the exhaust pipe, but sets the threshold at 105 decibels. At this decibel level, exposure should be limited to one hour a day. No state has adopted a regulation that takes into account wind noise.
In fact, several states have adopted regulations antithetical to the protection of riders from hearing loss. Use of a custom set of ear plugs is a well-known and effective way to suppress sound. Several states have made it illegal to operate a motor vehicle such as a motorcycle while wearing ear plugs in both ears. These regulations make no sense. Why protect one ear from hearing loss, but not the other? Also, at highway speeds wind noise will drown out any other noise that the rider might hear eliminating any safety benefit derived from such a regulation.
As noted above, wearing a standard motorcycle or snowmobile helmet will attenuate noise to a significant degree, but no enough to prevent fatigue, or temporary or permanent hearing loss. The fact that helmet manufacturers have not addressed hearing loss issues suggests other overriding factors exist including comfort, fashion, and the current regulatory framework. There certainly are other techniques which could be employed when designing helmets to reduce vehicle and wind noise. However, none heretofore known are both legal in all jurisdictions and widely acceptable to consumers.
Pilots and others working in close proximity to jet aircraft are exposed to even higher and more damaging sound levels, levels in excess of 140 decibels. Sound at this level not only can result in hearing loss but also significant pain. Various ear muffs have been employed to protect the hearing of those working in close proximity to jet aircraft. Likewise, various helmets have been employed having built-in ear muffs.
For example, U.S. Pat. No. 3,091,771 to Bixby discloses an aviator's helmet having ear cups for receiving and fitting around the ears of the aviator. Wire springs are used to attach the ear cups to the shell of the helmet. Cables with pull tabs extend through the shell of the helmet so the cups can be retracted from the ears when the helmet is doffed. The arrangement shown in Bixby offers several disadvantages. First, mounting of the springs and cables requires penetration of the shell of the helmet. Second, sound generated by movement of these parts will be transmitted to the ear cups. Third, donning and doffing the helmet becomes more difficult because the wearer is required to pull on the pull tabs while doing so to retract the ear cups.
U.S. Pat. No. 3,943,572 to Aileo and U.S. Pat. No. 4,700,410 to Westgate attempt to overcome the problems with the Bixby design by eliminating the springs, cables and pull tabs. The ear cups of the designs of the Aileo and Westgate patents are instead mounted on straps adjacent the wearer's ears. Aileo shows the ear cups mounted on the inside of the straps and foam cushioning pads mounted on the outside of the straps. The foam cushioning pads keep the ear cups from contacting the helmet shell. However, the pads will rub against the shell and transmit sound through the cup caused by such rubbing. In Westgate, the foam pads are replaced with an inflatable bladder attached to the shell. However, the shell will rub against the bladder causing sound generated by such rubbing to be transmitted to the wearer's ears. Also, both Westgate and Aileo incorporate straps to support the cups. Helmets without such straps, such as standard motorcycle and snowmobile helmets, cannot easily be retrofitted to confoLlu to what is shown in Aileo and Westgate.
Still another problem with the Westgate and Aileo systems is the space required to mount ear cups as shown. This is why the shells of the helmets shown in Westgate and U.S. Pat. No. 6,154,890 to Deopuria et al have pronounced outwardly projecting ear domes. While helmets used by aviators typically have such outwardly projecting ear domes, helmets used by motorcycle and snowmobile riders typically have shells with smooth, uninterrupted contours and without outwardly projecting ear domes. These helmets are designed to have a snug fit and a smooth exterior because it has heretofore been believed that these features provide the best noise attenuation value. Also, and from a fashion standpoint, snowmobilers and motorcyclists will not find helmets with protruding ear domes to be acceptable.
Therefore, it is desirable to provide an improved method and apparatus for protecting the hearing of the riders of recreational vehicles such as motorcycles, ATVs and snowmobiles and to accommodate such an apparatus within existing helmets used by such riders or in new helmets which would be acceptable from a comfort, safety and fashion standpoint.